I recommend these.
These have a solar charger. They can also be charged via USB port, if not exposed to enough sunlight. They contain an 18650 battery. I would get the model with a built in horn. These are the brightest light and the largest battery of the solar lights I have used. They can easily be detached from the bike and used as a flash light if you are camping. If I was doing a long trip, I would put 4 or 6 on the front of my bike. They don't add much weight. If you need to ride many hours in the dark, you can use one, then another, and another. 4 should last all night.